#include "stack.h"
void STInit(ST* ps)
{
	assert(ps);

	ps->a = (DataType*)malloc(sizeof(DataType) * 4);
	if (ps->a == NULL)
	{
		perror("malloc fail");
		return;
	}
	ps->capacity = 4;
	ps->top = 0;
}
void STDestroy(ST* ps)
{
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->capacity = 0;
	ps->top = 0;
}
bool STEmpty(ST* ps)
{
	assert(ps);
	return ps->top == 0;
}
void STPush(ST* ps,DataType x)
{
	assert(ps);
	if (ps->top == ps->capacity)
	{
		
		DataType*tmp = (DataType*)realloc(ps->a,sizeof(DataType) * ps->capacity*2);
		if (tmp == NULL)
		{
			perror("malloc fail");
			return;
		}
		ps->a = tmp;
		ps->capacity *= 2;
	}
	ps->a[ps->top] = x;
	ps->top++;
}
void STPop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));
	ps->top--;
}

DataType STTop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));

	return ps->a[ps->top - 1];
}
